This invention relates to a window regulator of the type used to raise and lower a window in a vehicle such as an automotive vehicle, and in particular to such a window regulator that has a long design life and an efficient braking system.
Window regulators are currently in wide spread use on vehicles such as cars and trucks. Conventional window regulators include a frame having a vertical guide portion which guides a traveller in movement between a raised position and a lowered position. A tension member such as a cable is secured to the traveller and passes around guide pulleys to a hub.
One type of window regulator employs a gear mechanism to rotate the hub. The hub is connected to a larger driven gear, which is driven by a smaller drive gear. The smaller drive gear in turn is rotated, typically by a manually operated crank arm or a motor.
In the past it has been conventional to use torsion springs positioned concentrically with the drive gear to engage an outer housing surrounding the gear, to form a type of drum brake. That is, the outer surface of the coil spring frictionally engages the inner surface of the surrounding housing to brake the window regulator and to prevent the weight of the window from causing the traveller to creep downwardly.
When window regulators of the type described above are used with unusually large, heavy windows certain wear problems are encountered. In particular, the bushings and the teeth of the drive gear may wear excessively. Furthermore, when the brake mechanism operates on the drive gear, the gear reduction provided by the gear linkage tends to make it more difficult for the brake to immobilize the traveller properly.
According, it is an object of this invention to provide an improved window regulator which can readily be serviced to provide extended life, and which provides a particularly efficient and effective brake mechanism.